The invention concerns generally the use of certain protocols and services for conveying certain types of information between the different nodes of a telecommunication network. Especially die invention concerns the preparations for and execution of the transmission of multimedia-related information between a terminal of a cellular radio network and a node computer of a fixed packet-switched network.
Multimedia is generally understood as the synchronized presentation of audiovisual objects to a user. It is typical to multimedia-related information that it may contain elements of highly different nature, lice text, still images, simple graphical elements, video and sound.
MMS or Multimedia Messaging Service is a proposed way for arranging the delivery of messages containing multimedia-related information from one telecommunication device to another. With xe2x80x9cmultimedia-relatedxe2x80x9d information we mean both the actual payload data that represents presentable objects and the control information that tells a presentation device how to handle the payload data. According to the proposals, MMS should be applicable for conveying such messages to and from the terminals of packet-switched cellular radio networks such as GPRS (General Packet Radio Service) and the packet-switched parts of UMTS (Universal Mobile Telecommunication System) in a store-and-forward manner much like the SMS (Short Messaging Service) text messages are conveyed in the second generation digital cellular networks, e.g. GSM (Global System for Mobile telecommunications).
FIG. 1 illustrates some system aspects of a known proposal for arranging the transmission of MMS messages between two mobile terminals (or generally: terminal arrangements) 101 and 102. In FIG. 1 each terminal is operating in a cellular telephone system of its own: terminal 101 is a UMTS terminal operating in a UMTS network 103 and terminal 102 is an enhanced GSM terminal operating in an enhanced GSM network 104. From both networks there is a connection to a GPRS network 105. The UMTS network 103 comprises a UTRAN or UMTS Terrestrial Radio Access Network 106 as well as a CN or Core Network 107. In the enhanced GSM network 104 a BSS or Base Station Subsystem 108 and an MSC or a Mobile Switching Centre 109 are shown. The detailed structure of the network elements is unessential to the present invention, but it is known that for example a UTRAN consists of a number of Radio Network Subsystems, each of which in turn comprises a Radio Network Controller and a number of Node Bs roughly corresponding to base stations. A BSS in turn comprises a Base Station Controller and a number of Base Transceiver Stations operating under it. Various mixed-mode cellular telephone systems are possible; for example the BSS 108 might operate under the same CN as the UTRAN 106. The terminals could also be exactly similar terminals operating close to each other in a single cell.
In FIG. 1 there is a connection both from the UTRAN 106 and from the BSS 108 to a corresponding SGSN or Serving GPRS Support Node 110 and 111. Both of these are in turn coupled, through the GPRS trunk lines, to a GGSN or Gateway GPRS Support Node 112 which here also operates as an MMSC or a Multimedia Messaging Service Center. In analogy with the known SMS arrangements a terminal 101 may transmit an MMS message by identifying both the intended recipient""s terminal 102 and the MMSC through which the message is to be transmitted (actually the latter may even be left out if there is a default MMSC for each terminal). A Packet Control Unit or a corresponding functionality in the UTRAN 106 takes the MMS transmission and routes it through the current SGSN 110 to the MMSC 112 which stores the MMS message and commences the attempts for delivering it to the intended recipient. If there is an existing connection to the recipient""s terminal 102 the MMSC may deliver the message through the corresponding SGSN 111 and the BSS 108 to the terminal 102. If, however, the terminal 102 is temporarily shut off, out of coverage or otherwise unreachable, the MMSC retries the delivery at certain time intervals until either the message is successfully delivered or a timeout expires indicating that the message is obsolete and can be deleted undelivered. A positive or negative acknowledgement, depending on the success in delivery, may be returned through the MMSC to the transmitting terminal 101 if required.
At the time of filing this patent application there does not exist an unambiguously defined way of using the lower-level protocol layers and PDP Contexts (Packet Data Protocol) in the terminals and fixed network devices to convey the MMS messages. Somewhere at a relatively high level in the protocol stacks of both the terminals and tie MMSC there must be an MMS-TP (Multimedia Messaging Service-Transport Protocol) entity that uses the services offered by the lower level protocols to convey an MMS message first from the transmitting device to the MMSC and then further to the receiving device. The actual name of the protocol entity may also be something else. Additionally the MMS messages must be mapped into PDP Contexts of certain type; the mapping will be closely related to the choice of lower protocol layers under the MMS-TP entity. We anticipate that network operators will require the MMS messaging to be distinguishable from other forms of packet-switched data transmission in order to arrange for a suitable charging scheme for the MMS services.
A prior art solution which has been proposed for conveying MMS messages is to have a PDP Type separately defined for MMS, and to set up a PDP Context of that type between a terminal and an MMSC each time an MMS message has to be conveyed in either direction. This approach has the drawback of requiring a considerable amount of completely new specification and standardization work. Additionally new PDP Types are only very reluctantly accepted to the already frozen standards.
It is an object of the present invention to provide a feasible method and a corresponding arrangement for setting up and configuring a connection suited for conveying MMS messages between terminals and MMSCs. It is an additional object of the invention that the proposed method does not require exhaustive respecification in the framework of existing standards and proposals.
The objects of the invention are met by using the IP or Internet Protocol PDP Context type, known as such, to carry a data stream comprising the required multiedia-related information, and by configuring the IP address of a MMSC to a terminal dynamically, most advantageously as a part of the PDP Context activation process.
The method according to the invention is characterized in that it comprises the steps of
defining a multimedia messaging transport protocol layer as a certain layer above the Internet Protocol layer in certain first and second protocol stacks so that the defined multimedia messaging transport protocol layers are peer entities and
exchanging multimedia-related information between the multimedia messaging transport protocol layer in a terminal arrangement and the multimedia messaging transport protocol layer in a network device arrangement through the use of additionally defined Internet Protocol layers as well as other lower layers in the first and second protocol stacks.
The invention also applies to a terminal which is characterized in that its control block is arranged to
implement a multimedia messaging transport protocol layer in a protocol stack and
exchange multimedia-related information between said multimedia messaging transport protocol layer in the protocol stack and a certain network device arrangement through the use of an Internet Protocol layer as well as other lower layers in the protocol stack.
Additionally the invention applies to a network device which is characterized in that its control block is arranged to
implement a multimedia messaging transport protocol layer in a protocol stack and
exchange multimedia-related information between said multimedia messaging transport protocol layer in the protocol stack and a terminal arrangement through the use of an Internet Protocol layer as well as other lower layers in the protocol stack.
The Internet Protocol or IP is a well-known protocol for routing packet data through a data transmission network. The GPRS standards and proposals that are available to the public at the priority date of this patent application describe the activation and use of a specific PDP Context type for carrying IP packets. According to the invention a PDP Context of the IP type is activated also for the transmission of multimedia-related information. On the basis of the contents of a request message the network devices (mainly the SGSN) are able to route a request for the activation of a PDP Context to an MMSC. As a part of the known PDP Context activation process such an MMSC transmits a response, and according to the invention it indicates its IP address (or the IP address of another, more suitable MMSC) within said response. Dynamic IP address allocation is most advantageously applied to allocate an IP address to the terminal that initiated the PDP Context activation. The dynamically allocated IP address of the terminal is indicated to the MMSC, whereafter the IP addresses of the communicating parties are known to each other and the activated PDP Context of the IP type may be used to transmit multimedia-related information.
The invention has several advantageous features. The dynamic indication of the IP address of the MMSC at the PDP Context activation stage enables more flexible and optimal routing of MMS traffic in the cases where the terminal arrangement is roaming, because the terminal can connect also to other MMSCs than the xe2x80x98homexe2x80x99 MMSC. The invention also avoids static storage of MMSC addresses within the user""s terminal or Subscriber Identity Module (SIM), because the MMSC address can be dynamically configured to the MS, The dynamic configuration of MMSC addresses also allows the operator to reconfigure the network and MMSCs to be used for message delivery. Some MMSCs can be e.g. run down in maintenance while other MMSCs take responsibility of the users. Controlled distribution of users and message load is also possible in the suggested solution. The network can dynamically distribute users among a certain group of processing units and/or MMSCs by just allocating different IP addresses for different users.